Absolutely Java and JavaScript since they will strengthen your understanding of Clojure(Script). Knowing what the JVM is capable of and having the option of dropping down to Java if you really need to do something performance critical is like having a super power. You don’t need to do it often but having the option to do so is great. Same applies to JS. Knowing how and when to leverage the Host is critical IMHO.
Besides that I’m fond of Erlang. The real Erlang not others based on it like Elixir. It is a rather niche Language and definitely best suited for very high concurrency network type application (eg. many millions of connections). It was built for that and the programming model reflects that. I wouldn’t call it a general purpose platform but for its niche its nice.
But to be honest every language I used in my carreer taught me something valueable. I would never want to use PHP again but it would still be valuable to learn since it is still one of the simplest ways to get something going on the web.